Bituminous pavement and method of making the same



Patented Dec. 1, 1936 UNITED STATES PATENT OFFICE BITUMINOUS PAVEMENT AND METHOD OF MAKING THE SAIWE No Drawing. Application February 11, 1932, Serial No. 592,447

7 Claims.

This invention relates to a method of producing cold mixed and cold laid bituminous roadways or pavements. A particular object of this invention is to uniformly incorporate the differout ingredients of the mixture by priming the mineral aggregate with a non-volatile oil and mixing in powdered asphalt without the application of heat, all under conditions to provide a wide range of adaptability.

10 Another object of this invention is to first prime mineral aggregate with a non-volatile oil that-will easily wet all types of mineral matter or road metal, such as sand, gravel and crushed stone.

Other objects of the invention are as follows:

To so treat the priming oil that it will cover mineral aggregate that contains a small amount of water;

To use a non-volatile primer that is a good solvent for the powdered asphalt and combines readily with the solid asphalt particles under pressure or traffic without application of heat.

Additional features of the invention will be apparent from the following description. I have found that priming oil and powdered asphalt derived from the same source will give better and safer combinations. Cracking coil tar is given in the appended examples as the chief source for the primer and powdered asphalt,

though tar or the like derived from other sources may be used. This cracking coil tar is the residual oil when petroleum oils are distilled after being cracked in vapor, liquid or liquid and vapor phase at temperatures ranging from about 800 I F. to 1000 F., and under pressures ranging from atmospheric to 2000 pounds per square inch.

In apreferred form of the invention, the primy ing oil is a straight cracking coil tar derived from 1 petroleum gas oil feed and having Furol viscosities ranging from about 100 to 500 seconds at 122 F. The powdered asphalt is a straight cracking coil tar asphalt from gas oil feed, first .reduced to about 180 and 220 penetration, then oxidized and having melting points ranging from 200 F. to 250 F. The asphalt is powdered, for example, to pass through a mesh screen. The mineral aggregates used are crusher run gravel containing fineparticles, sand passing 10 mesh screen and including natural fines, crusher run 50 stone with or without the particles below 54; inch, and sand including all fines.

The priming oil is preferably treated with substances such as soap, alkalis, fatty acids, sulphonated oils of all types, etc. This treatment low- 55 ers the surface tension of the priming oil and increases the spreading qualities to a point where it will coat satisfactorily mineral matter in moist or wet condition.

The method of laying the roadways or pavements is as follows: The proportions of the prim- 5 ing oil with or without the emulsifying agent, and the powdered asphalt to form homogeneous mixtures of the desired penetrations, such as 45 to 55, to and to 220 at 77 F., are determined. The amounts of priming oil and pow- 10 dered asphalt required to make a mixture of the desired penetration are determined by making three mixtures of varying proportions of the two ingredients. The penetrations of the resulting mixtures are taken and by plotting these values 5 the exact proportions of ingredients necessary to obtain approximately 50, 100 and 200 penetration samples are obtained.

The mineral aggregate of either crusher run stone, crusher run gravel or sand (as described above) or a mixture of two or three of these ingredients is selected. The choice of these ingredients is dependent on the type of pavement that is to be laid and if the mixture is to be used as a base or a wearing surface of said pavement.

The mineral aggregate is thoroughly mixed with a predetermined amountof priming oil that is required to make a certain penetration asphalt mixture. No heat is applied in the mixing. The determined amount of powdered asphalt to make the above penetration asphalt mixture is admixed with first mixture of mineral aggregate and priming oil. The final mixing of the three ingredients is continued until it is evident that the powdered asphalt is thoroughly distributed. All this is done at atmospheric temperature without addition of heat. The resulting mixture is then applied as a pavement and suitably compressed, such as by rolling with a ten ton, three wheeled roller until it is no longer pliable.

A fraction of the predetermined amount of priming oil suflicient to wet the mineral aggregate may be first mixed with the mineral aggregate. The remaining fraction of priming oil and the predetermined amount of powdered asphalt may 46 then be added and admixed until uniformly incorporated through the entire mass.

The mixture of mineral aggregate, priming oil and asphalt, after being incorporated may be stored or transported to the point of application. 50 The mixture does not solidify without the application of pressure.

The presence of varying quantities of moisture do not aifect this mixture where an emulsifying agent is incorporated with the priming oil. The 55 finished bituminous mixture may be spread out on the road and turned over a few times in order to eliminate this moisture if it is found to be detrimental to setting or otherwise. If the moisture present does not amount to over it is not necessary to turn over the mixture, as in spreading out the aggregate sufficient of the entrapped moisture is lost to give a' thorough set.

In preparing an asphalt mixture of the desired penetrations with an oil and powdered asphalt derived from cracking coil tar the following proportions were used:

These proportions are given by way of illustration as the proportions vary as to the source of the tar from which the priming oil and powdered asphalt are derived.

The proportions of the asphalt mixture and the mineral aggregate vary as to local climatic conditions and type of pavement desired though no greater percentage than of the asphalt mixture to 90% of the mineral aggregate are known to be used. The general proportions are about 5% of asphalt mixture and 95% of mineral aggregate.

By this invention bituminous pavements are produced without the application of heat. The use of a priming oil that dissolves the powdered asphalt uniformly incorporates the mixture throughout the resulting mass due to the solvent action of the priming oil.

The foregoing description is merely illustrative and various changes and alternative procedures may be made within the scope of the appended claims in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

1. The production of bituminous paving mixture that solidifies on application of heat which comprises adding a wetting agent to a priming oil having a F'urol viscosity of 100 to 500 seconds at 122 F., determining the amounts of the priming oil with the wetting agent and powdered asphalt having melting points ranging from 200 to 250 F. to make a definite penetration asphalt mixture, mixing the predetermined amount ofpriming oil and wetting agent with a mineral aggregate, and

vmixing the predetermined amount of powdered asphalt with the mineral aggregate and priming oil mixture, without the addition of heat.

2. Method of laying a bituminous pavement or roadway that solidifies on application of pressure, comprising mixing with wet road metal a priming oil having a Furol viscosity of 100 to 500 seconds at 122 F. adapted to coat the same, and then mixing asphalt having melting points ranging from 200 to 250 F. with the coated road metal under conditions to form a pressure bond without the application of heat.'

3. The production of a bituminous paving mixture that solidifies on application of pressure, which comprises mixing priming oil having a Furol viscosity of 100 to 500 seconds at 122 F. and powdered asphalt having melting points ranging from 200 to 250 F. derived from the same source with mineral aggregate and a wetting agent, without the addition of heat.

4. The production of a bituminous paving mixture that solidifies on application of pressure, which comprises determining the amount of priming oil having a Furol viscosity of 100 to 500 seconds at 122 F. and powdered asphalt having melting points ranging from 200 to 250 F. to'make a definite penetration asphalt mixture, mixing the predetermined amount of priming oil and a wetting agent with a mineral aggregate, and mixing the predetermined amount of powdered asphalt with the mineral aggregate and priming oil mix-' ture, without the addition of heat.

5. The production of a bituminous paving mixture that solidifies on application of pressure, which comprises determining the amount of priming oil having a Furol viscosity of 100 to 500 seconds at 122 F. and powdered asphalt having melting points ranging from 200 to 250 F., derived from the same source, to make a definite penetration asphalt mixture, mixing the predetermined amount of priming oil and a wetting agent with a mineral aggregate, and mixing the predetermined amount of powdered asphalt with the mineral aggregate and priming oil mixture, without the application of heat.

6. The production of a bituminous paving mixture that solidifies on application of pressure, which comprises determining the amount of priming oil having a Furol viscosity of 100 to 500 seconds at 122 F. and powdered asphalt having melting points ranging from 200 to 250 F. to make a definite penetration asphalt mixture, mixing a fraction of the predetermined amount of priming oil and a wetting agent with a mineral aggregate, and mixing the remaining fraction of priming oil, together with the predetermined amount of powdered asphalt, with the priming oil and mineral oil aggregate, without the addition of heat.

7. Method of laying a bituminous pavement or roadway, comprising mixing with wet road metal a priming oil having a Furol viscosity of 100 to 500 seconds at 122 F. and a wetting agent, mixing asphalt having melting points ranging from 200 to 250 F. with the mixture of wet road metal, priming oil and wetting agent, laying the mixture in layers and applying pressure, without the addition of heat.

CHARLES M. BASKIN. 

